Hot Springs Sprung Life?
Berardelli, Phil, Insight on the News
Scientists long have puzzled about the Great Question: How did life on Earth begin? Did it spring forth spontaneously in ocean currents or shallow undulating tidal pools, or was it scalded into existence by deep-sea volcanic fountains?
Recently, 25 researchers from nine countries aboard the drill ship JOIDES Resolution accidentally may have found important clues to this fundamental riddle. The expedition was exploring the ocean bottom 150 miles west of Vancouver Island, Canada, pulling up drill cores from the seafloor to analyze mineral and biological deposits. But the drilling reactivated hydrothermal vents, and superhot water of 550 degrees Fahrenheit spewed forth through the core holes.
Natural hot springs on the seafloor interest scientists because they are a means to study the accumulation of iron, copper, zinc and manganese - mineral deposits found in new oceanic crust. More important, these deposits seem tied to tectonics - the process by which continental plates drift and collide over eons - and maybe to the genesis of life itself.
The motion of the plates produces cracks in the Earth's crust. When these cracks occur on the seafloor, water penetrates them, becomes superheated when it hits hot volcanic rock and then returns to the ocean carrying minerals through hydrothermal vents. Over millions of years, as the processes of tectonics and sedimentation proceed, the deposits may end up buried under dry land.
"One thing we don't know is how far down the water has to travel to become superheated," says Bruce Malfait, director of the National Science Foundation's Ocean Drilling Program, which sponsored the expedition. The core drilling was supposed to help answer that question, but the creation of the new vents is regarded as a serendipitous opportunity to study the process from the beginning.
Geologists hope to discover more about "how metallic ore deposits that we mine on land were formed millions of years ago," according to Robert Zierenberg, a researcher with the University of California at Davis and co-chief scientist of the expedition. But biologists are interested in the vents as well. Some speculate hydrothermals represent the location where life first appeared some 3.5 billion years ago.
If so, the newly discovered vents may offer clues to an ancient mystery: Since hydrothermals are known to have limited life spans, how did biological organisms have enough time to evolve in their heat? And if they didn't have enough time, did they migrate from vent to vent?
Melanie Summit, a microbiologist at the University of Washington, believes the Vancouver vents could provide some answers."We can now start from time zero and watch how these sites become colonized," she says. "This is our first opportunity to see how a new hydrothermal vent, and the animal communities that thrive in these environments, grow and change with time."
The National Science Foundation is arranging for scientists to begin visiting the site on a regular basis. …